FIG. 1A, FIG. 1B are a schematic external view showing a configuration example of the above-described traveling crane. The illustrated traveling crane 100 has travel rails 101 laid in a predetermined direction (e.g. east-west direction) in the horizontal plane of the ceiling of a building, a traverse rail (girder) 102 disposed in a direction (e.g. south-north direction) perpendicular to the travel rails 101 and moved along the travel rails 101 by geared motors (travel motors) 103, and an electric hoist 106 having a traverse motor 104 for traversing along the traverse rail 102 and an elevation motor 105 for lifting and lowering a load.
In the traveling crane 100, the electric hoist 106 has a control box 107 connected thereto through a cable 108 or the like. The control box 107 is equipped with pushbutton switches “East”, “West”, “South”, “North”, “Up” and “Down”, for example. In response to the operation of the pushbutton switches “East”, “West”, “South” and “North”, the electric hoist 106 travels in the east-west direction along the travel rails 101 and traverses in the south-north direction along the traverse rail 102. In response to the operation of the pushbutton switches “Up” and “Down”, a load (not shown) suspended by a load-suspending hook 109 is lifted and lowered (hoisted up and down). It should be noted that FIG. 1A is a schematic general view showing a configuration example of the traveling crane, and FIG. 1B is an enlarged view of a part of the traveling crane, showing the control box 107.
With the traveling crane arranged as stated above, it is necessary to find out a pushbutton switch corresponding to a direction (travel, traverse, lifting or lowering direction) in which a load (object to be transported) suspended by the load-suspending hook 109 is to be moved from among the pushbutton switches “East”, “West”, “South”, “North”, “Up” and “Down” attached to the control box 107. When the electric hoist 106 is operated in both the travel and traverse directions, two pushbutton switches need to be pressed simultaneously. There is another problem that fine speed control for travel, traverse, lifting and lowering cannot be performed.
There is a traveling crane as disclosed in Patent Literature 1, which enables an operator of the traveling crane to translate a transport object in a desired direction simply by adjusting the direction of a control box while pressing a switch and looking in the direction of movement of the transport object moving being suspended by a hook, without the need to look at his or her hand. FIG. 2 is a schematic external view showing a configuration example of the traveling crane disclosed in Patent Literature 1. The illustrated traveling crane 200 has travel rails 201 laid in a predetermined direction in the horizontal plane of the ceiling of a building, a traverse rail (girder) 203 disposed between a pair of saddles 202 traveling along the travel rails 201 through wheels, and an electric hoist 204 traversing along the traverse rail 203 through wheels. A load-suspending hook 206 is secured to the distal end of a support wire rope 205 that is wound up by the electric hoist 204. A communication cable 207 that is bendable but not twistable is suspended from the electric hoist 204 to near the floor surface. A control box 210 is connected to the lower end of the communication cable 207 through a rotatable rotary joint 209.
The front of the control box 210 is provided with a two-step pushbutton control switch 211 and also provided with a lifting (hoist-up) switch and a lowering (hoist-down) switch disposed at the upper and lower sides, respectively, of the control switch 211. When the control switch 211 is pressed, an X-axis motor or a Y-axis motor operates to move the electric hoist 204 horizontally in a direction opposite to the direction in which the control box 210 faces, i.e. a direction opposite to the forward direction of the control box 210. Accordingly, the operator can translate the transport object in a desired direction by adjusting the direction of the control box 210 while pressing the switch and looking in the direction of movement of the transport object moving being suspended by the load-suspending hook 206, without the need to look at his or her hand.